Entropy characteristics are investigated during the tropical cyclone Haiyan (TCH) using the weather research and forecasting (WRF) model in a downscaling experiment with two nests, 18- and 6-km grid spacing. This TC was stronger than most Saffir–Simpson category 5 typhoons. In this research, entropy, air–sea thermodynamic disequilibrium (ASTD) and entropy fluxes (including surface, convective and lateral entropy fluxes) have been analyzed. Scale analysis of these parameters has been done using integrated values over two types of areas including fixed square-ring areas and circular structural-based areas, all surrounding TCH center. The considered parameters (using downscaled data with 6-km grid spacing) integrated over the various areas showed the maximum or minimum value with various lag or lead times, comparing with TCH peak intensity (at 18:00 UTC 07 November, when TCH made landfall in the Philippine Islands). In addition, the multiscale analysis emphasized that entropy transport between different parts of TCH could not be ignored. Most of the considered parameters integrated over the larger areas reached the extremum values before TCH maximum intensity. Integrating over the fixed square areas led to that more parameters got the extremum value before TCH greatest intensity comparing with those integrated over the circular structural-based areas. This indicates that it is unnecessary to focus only on the circular structural-based areas. Conclusively, hierarchy of derived extremum values of entropy and its derivations over the various scales (especially those integrated over the fixed square areas) showed that this parameter could be served as a relevant proxy parameter and its evolution is worthwhile to be considered in TC investigation.

中文翻译：

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强烈热带气旋期间的熵演化特征

在热带气旋海燕 (TCH) 期间，使用天气研究和预报 (WRF) 模型在两个巢穴、18 公里和 6 公里网格间距的缩小实验中研究了熵特征。该 TC 比大多数 Saffir-Simpson 5 级台风更强。在这项研究中，对熵、海气热力学不平衡 (ASTD) 和熵通量（包括表面、对流和侧向熵通量）进行了分析。这些参数的尺度分析是使用两种类型区域的积分值完成的，包括固定方环区域和基于圆形结构的区域，所有区域都围绕 TCH 中心。与TCH峰值强度（在18：00 UTC 11 月 7 日，当 TCH 在菲律宾群岛登陆时）。此外，多尺度分析强调了TCH不同部分之间的熵传递不容忽视。在较大区域上积分的大多数考虑参数在 TCH 最大强度之前达到极值。与基于圆形结构区域的积分相比，在固定正方形区域上积分导致更多参数在TCH最大强度之前获得极值。这表明没有必要只关注基于圆形结构的区域。最后，